Prospects for a filibuster to try to derail Samuel Alito’s confirmation to the Supreme Court all but died yesterday when a key swing Democrat, Dianne Feinstein, came out against it.

“I do not see a likelihood of a filibuster,” the California senator said on CBS’s “Face the Nation.” “This might be a man I disagree with, but it doesn’t mean he shouldn’t be on the court.”

Feinstein said she would vote against the confirmation, but admitted to being impressed with Alito’s “very even demeanor” at last week’s hearings.

It takes 41 votes to block a nominee by filibuster, and the Democrats have 45. But several Democrats have spoken out against the strategy – and the defection of a pro-choice woman like Feinstein would seem to make it all but impossible.

Still, if the Democrats don’t at least try to filibuster, they risk further angering liberal activists and bloggers who have already accused them of doing a lousy job of questioning Alito.